Re: [RFC][PATCH 2/7] VPIDs: pid/vpid conversions

[Kirill Korotaev <dev@sw.ru>]

>>The only correct thing you noticed is get_xpid on alpha. But this is
>>in fact a simple bug and half a year before we didn't care much for
>>archs others than i386/x86-64/ia64. That's it.
> sidenote on that, maybe the various archs could
> switch to C implementations of those 'special'
> get_xpid() and friends, as I do not think they
> are a) done that often (might be wrong there)
> and b) recent gcc should get that right now anyway
I also wonder why it was required and can't be done in normal way...
Maybe worth trying to switch to C, really.

>>For example, networking is coupled with sysctl, which in turn are
>>coupled with proc filesystem. And sysfs! You even added a piece of code
>>in net/core/net-sysfs.c in your patch, which is a dirty hack.
>>Another example, mqueues and other subsystems which use netlinks and 
>>also depend on network context.
>>shmem/IPC is dependand on file system context and so on.
>>So it won't work when one have networking from one container and proc
>>from another.
> the question should be: which part of proc should be part
> of the pid space and which not, definitely the network
> stuff would _not_ be part of the pid space ...
Ok, just one simple question:
how do you propose to handle network sysctls and network 
statistics/information in proc?
_how_ can you imagine this namespaces should work?
I see no elegant solution for this, do you? If there is any, I will be 
happy with namespaces again.

>>So I really see no much reasons to have separate namespaces, 
>>but it is ok for me if someone really wants it this way.
> the reasons are, as I explained several times, that folks
> use 'virtualization' or 'isolation' for many different
> things, just because SWsoft only uses it for VPS doesn't
> meant that it cannot be used for other things
Out of curiosity, do you have any _working_ examples of other usages?
I see only theoretical examples from you, but would like to hear from 
anyone who _uses_/_knows_ how to use it.

> just consider isolating/virtualizing the network stack,
> but leaving the processes in the same pid space, how to
> do that in a sane way with a single reference?
I see... Any idea why this can be required?
(without proc? :) )
BTW, if you have virtualized networking, but not isolated fs namespace 
in this case, how are you going to handle unix sockets? Or maybe it's 
another separate namespace?

>>1. ask Linus about the preffered approach. I prepared an email for him
>>with a description of approaches.
> why do you propose, if you already did? :)
because, the question was quite simple, isn't it?

>>2. start from networking/netfilters/IPC which are essentially the same
>>in both projects and help each other.
> no problem with that, once Eric got there ...

Kirill